Sand-blast apparatus.



PATENTED NOV. 1, 1904.

J. E. MATHBWSON. SAND BLAST APPARATUS. APPLICATION FILED 1350.9, 1903.

2 SHEETS-SHEET 1.

N0 MODEL.

Patented November 1, 1904;.

PATENT @rrrca.

JEREMIAH EUGENE MATHEWSON, OF BROADHEATH, ENGLAND.

SAND-BLAST APPARATUS.

SPECIFICATION forming part of Letters Patent No. 773,663, dated November1, 1904. Application filed December 9, 1903. Serial No. 184,409. (Nomodel.)

To all 1071,0722, it away concern;

sieving device.

The use of the sand-blast for cleaning castings is now well known;butithas been found desirable when large castings are to be cleaned toprovide a room or chamber in which the castings are placed and in whichthe attendant stands to direct the stream of sand onto the castings. Oneof the drawbacks in the use of the sand-blast for this purpose is thelarge amount of dust produced, due to the pulverization of the cuttingor abrading material, the molding-sand, and the scale on the surface ofthe article to be treated. This pulverized material (dust and very finesand) if used again absorbs a considerable amount of power to project itand produces but little or no good efifect, because of its extremefineness. The repeated use of this fine sand and dust also causes acloud of dust to arise in the chamber, which renders it unfit to workin,and, moreover, the operator is unable to see what he is doing.

Now the object of the present invention is .to construct a sandblastapparatus of the most complete character, in which provision will bemade to prevent this cloud of sand arising by automatically andcontinuously separating thecutting and abrading material from the dustand fine sandwvhich hamper its action. To this end a current of air iscaused to pass by suction through the working chamber or room from aboveto below to draw the dust and fine sand downward to collecting-hoppers,into which the cutting-sand will drop by gravity and from which the sandand dust are conveyed by the same current to a cyclone-separator and asieving device,

so that an entire separation of the air, dust, and fine sand from thecutting-sand takes place.

In carrying out this invention the chamber is formed with suitableinlets in the roof and a perforated floor, below which are thecollectinghoppers in connection by suitable pipes with a suction deviceof convenient character and with the cyclone and sieving apparatus.

In order that the invention may be clearly understood, Iwill nowdescribe the apparatus with reference to the accompanying drawings.

A is a pit in which the sand-blast apparatus proper, B, is placed. Thisapparatus is preferably of the character described in the specificationof Letters Patent granted to me, dated December 25, 1894, No. 531,379,in which a pressure of air both above and below the sand is provided toinsure the proper running of the sand. Supported on suitable girdersover the pit is the working chamber G, which is provided, preferably,with a glass roof D and a door or doors E. In the roof are openings Ffor the entrance of air, and below the openings are arranged in aninverted position conical baffles G, which have the double function ofpreventing the outward escape of the flying sand and also of collectingany that may find its way to the roof and return it to the chamber, forwhich purpose the apex of the cone is removed to leave a small holethrough which the sand can pass. The fioor of the chamber consists ofperforated plates or gratings H, below which are placed hoppers I inconnection with an exhaust-pipe J. This exhaust-pipe J is connected witha cyclone apparatus K, into which the current of air carrying the sandand dust enters at a tangent, whereby centrifugal action caused by theexhausting of the air at L is set up. In this apparatus the sand isseparated from the air, which carries with it the finest of the dust.The sand thus robbed of the air and a certain proportion of the dustdrops into the hopper-shaped bottom of the apparatus K, where it isretained by a sliding valve N until required for use. This valvealsoserves to regulate the passage of the sand to a mechanical sievingapparatus O, as will be presently explained. Above the outlet of thecyclone apparatus K is fixed by suitable stays a cone P, which willserve to arrest upward currents of air from the sieving apparatus 0 andprevent their passing to the exhaust L should the sand in thehopper-bottom of K become exhausted.

The sieving apparatus 0 consists of an oblong chamber with atrough-shaped bottom having a narrow longitudinal slit. as will be seenin the cross-section, Fig. 3. This chamber is open at one end and isconnected at the other end with the exhaust L by a pipe L, in which is avalve L Below the inlet 0 to this chamber are deflecting-plates Q, whichserve to spread the falling sand and dust so as to form a thin curtainof sand and dust. It will be obvious that in this curtain of sand anddust there will be heavier particles and lighter particles, the heavierrepresenting the cutting and abrading sand and the lighter the uselessfine sand and dust. The exhaustLbeing opened through valved pipe L, acurrent of air will be drawn in at the open end of the chamber 0 andthrough this curtain of sand. This current of air will have little or noef feet on the heavier or usable or cutting particles, which will dropat once of their own weight to the bottom of the chamber 0 and thencethrough the slit into the hopper of the sand-blast apparatus proper, B.The lighter particles will, however, be carried forward by the currentof air toward the outlet L of the chamber and will deposit in the bottomof the chamber at a part which extends be-, yond the edge of the hopperof the apparatus B, from which part the line sand and dust are allowedto drop into a pit or container R, suitably arranged to receive them andfrom which the deposit may be removed by a shovel or in any otherconvenient manner as and when desired.

The limit of size of the usable particles of the sand may be regulatedby means of a chute or inclined plate S. (See Figs. 1 and 3.) This chuteS is carried by external flanges on the bottom of the chamber 0 and canbe shifted farther from or nearer to the outlet L, as oocasion mayrequire. The chute S will act as a kind of partition to divide theheavier from the lighter particles, and all the lighter particlescarried beyond its upper edge by the current of air will be guided intothe pit R, while the heavier particles will drop in front of thepartition into the hopper of B.

T is a rod which extends into the room (I, by which the workman mayoperate the valve to allow the sand to pass into the closed chamber ofB. U is another rod by which the sand-valve of the apparatus B isoperated, also from the room U.

Vis the compressed-air pipe, which opens into the apparatus B at twopoints, as described in the specification of patent before referred to.

TV is the blast-pipe, which is provided at its outer end with a flexiblepipe and nozzle X. (See Fig. 2.)

V is a valve-rod extending into the room G for operating a valve in thecompressed-air pipe V as and when desired.

\Vhat I claim as my invention, and desire to secure by Letters Patent,is-

1. In a sand-blast apparatus for cleaning castings the combination witha sand-blast machine and a chamber in which the castings are cleaned,having collecting-hoppers and a suction-pipe, of a cyclone-separator forseparating the air and the finer dust from the cutting-sand and anair-sieving device arranged to receive the residual sand from saidseparator and to complete the separation of the cutting-sand from theunusable fine sand and dust. as set forth.

2. In combination with a sand-blast apparatus, the air-sieve apparatus,as shown and described and consisting of an oblong chamber open at oneend to the atmosphere and connected at the other to a suction device,having a sand-inlet at top and a longitudinal outlet-slit at bottom, incombination with transverse deflectors to spread the falling sand and achute adjustable longitudinally along the outlet-slit, as set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

JEREMIAH EUGENE llIA'lliEWSON.

Witnesses:

H. E. NEWTON, A. (Jos'rA.

